For Winodws/MacOS, a virtual image with udp2raw pre-installed has been released, you can load it with Vmware/VirtualBox.The virtual image has been set to auto obtain ip, udp2raw can be run immediately after boot finished(make sure network mode of virtual machine has been set to bridged)(only udp2raw has to be run under a virtual machine, all other programs run under Windows/MacOS as usual).

Features

Send / Receive UDP Packet with fake-tcp/icmp headers

Fake-tcp/icmp headers help you bypass UDP blocking, UDP QOS or improper UDP NAT behavior on some ISPs. Raw packets with UDP headers are also supported.In UDP header mode, it behaves just like a normal UDP tunnel, and you can just make use of the other features.

Simulate TCP Handshake

Simulates the 3-way handshake, along with seq and ack_seq. TCP options MSS, sackOk, TS, TS_ack, wscale are also simulated. Real-time delivery guaranteed, no TCP over TCP problem when using OpenVPN.

Encryption, Anti-Replay, No MITM

Encrypt your traffic with AES-128-CBC.

Protect data integrity by MD5 or CRC32.

Defense replay attack with an anti-replay window, similar to IPSec and OpenVPN.

Authenticate mutually, no MITM attacks.

Failure Detection & Stabilization (Connection Recovery)

Connection failures are detected by heartbeats. If timed-out, the client will automatically change port number and reconnect. If reconnection is successful, the previous connection will be recovered, and all existing UDP conversations will stay valid.

For example, if you use UDP2RAW + OpenVPN, OpenVPN won't lose connection after any reconnect, even if the network cable is re-plugged or the WiFi access point is changed.

Other Features

Multiplexing One client can handle multiple UDP connections, all of which share the same raw connection.

Multiple Clients One server can have multiple clients.

NAT Support All of the 3 modes work in NAT environments.

OpenVZ Support Tested on BandwagonHost.

OpenWRT Support No dependencies, easy to build. Binary for ar71xx are included in release.

Now, an encrypted raw tunnel has been established between client and server through TCP port 4096. Connecting to UDP port 3333 at the client side is equivalent to connecting to port 7777 at the server side. No UDP traffic will be exposed.

IPTABLES rule This program sends packets via raw socket. In FakeTCP mode, Linux kernel TCP packet processing has to be blocked by a iptables rule on both sides, otherwise the kernel will automatically send RST for an unrecongized TCP packet and you will sustain from stability / peformance problems. You can use -a option to let the program automatically add / delete iptables rule on start / exit. You can also use the -g option to generate iptables rule and add it manually.

cipher-mode and auth-mode It is suggested to use aes128cbc + md5 to obtain maximum security. If you want to run the program on a router, you can try xor + simple, which can fool packet inspection by firewalls the most of time, but it cannot protect you from serious attacks. Mode none is only for debugging purpose. It is not recommended to set the cipher-mode or auth-mode to none.

seq-mode The FakeTCP mode does not behave 100% like a real tcp connection. ISPs may be able to distinguish the simulated tcp traffic from the real TCP traffic (though it's costly). seq-mode can help you change the seq increase behavior slightly. If you experience connection problems, try to change the value.

Peformance Test

Test method: iperf3 TCP via OpenVPN + udp2raw (iperf3 UDP mode is not used because of a bug mentioned in this issue: https://github.com/esnet/iperf/issues/296 . Instead, we package the TCP traffic into UDP by OpenVPN to test the performance. Read Application for details.

speed-up tcp connection via raw traffic by using udp2raw+kcptun kcptun is a tcp connection speed-up program, it speeds-up tcp connection by using kcp protocol on-top of udp.by using udp2raw, you can use kcptun while udp is QoSed or blocked. (kcptun, https://github.com/xtaci/kcptun)

speed-up tcp connection via raw traffic by using udp2raw+finalspeed finalspeed is a tcp connection speed-up program similiar to kcptun, it speeds-up tcp connection by using kcp protocol on-top of udp or tcp.but its tcp mode doesnt support openvz, you can bypass this problem if you use udp2raw+finalspeed together, and icmp mode also becomes avaliable.